Heat transfers



June 1961 R. G. SHEPHERD, JR 2,989,413

HEAT TRANSFERS Filed Oct. 6, 1958 ff PRINTED DESIGN fl-UNOXIDIZEDFISCHER-TROPSCH WAX VIIIIIIIIIIM m\\\\\\\\\ fl-PAPER BAcKER Java/war .66 ep/Zeruf, 17;: j

United States Patent 2,989,413 HEAT TRANSFERS Ridgley G. Shepherd, In,Weston, Mass, assignor to Dennison Manufacturing Company, Flamingham,Mass., a corporation of Massachusetts Filed Oct. 6, 1958, Ser. No.765,500 2 Claims. (Cl. 1173.2)

The present invention relates to heat transfers and particularly toimprovements in heat transfers embodying a wax release coating, thisbeing a continuation-inpart of Ser. No. 630,276, filed December 24,1956, which has been abandoned.

The objects of the present invention are to provide an improved heattransfer embodying a wax release layer, to provide an inexpensive heattransfer receptive to high quality printing, to provide a heat trans-ferwhich can be readily printed on conventional equipment and withconventional inks, and to provide a heat transfer which can betransferred to impermeable as well as permeable surfaces without theneed for special adhesive layers over the printed design and withoutneed for sizings on the paper carrier.

Heat transfer products embodying release coatings of wax have long beenknown but, with the exception of the oxidized wax transfers disclosedand claimed in my copending Patent 2,862,832, granted December 2, 1958,the products heretofore disclosed have possessed severe limitationswhich have prevented their widespread use. One limitation has been thedifficulty in printing due to ink striking into the wax during printing,ink migration into the wax after printing, ink crawling on the waxsurface, wax oifset during storage, and picking and embossing of the waxduring printing.

A further limitation in prior wax transfers, other than the transfers ofthe aforesaid patent, has been the faulty transfer of the design,particularly where the surface to be labeled is smooth and impermeable.This faulty transfer is commonly manifested as an ink-split with part ofthe design transferring and part remaining on the backing or carrier.Attempts have been made to remedy this latter limitation by using heavywax layers but this increased the distortion of the design duringtransfer and promoted wax staining of the surface being labeled. Heavyimage layers which were intended to split have also been used but finereproduction detail is impossible with such materials. Images with highstrength properties overlayed with adhesive coatings have also beendisclosed but these are expensive and are difiicult to apply withconventional printing equipment. Finally, impermeable paper backing orcarriers such as glassine and coated papers have been suggested toovercome the drawbacks of wax transfer coatings but such materials arenot entirely satisfactory and increase the cost of the product.

Thus ideally a wax release coat should be inexpensive, be effective inthin films as a release agent when coated on inexpensive paper, bereceptive to high quality printing, resist strike through or migrationof an ink design, have low staining properties, resist picking duringprinting, show no offset tendency during storage, and be easy to applyon production equipment. None of the prior disclosures, except theaforesaid patent, meet all of these requirements.

According to the present invention, the above require ments and objectsare met by a heat transfer comprising a backing and thereon a releasecoating comprising unoxidized Fischer-Tropsch wax. The coating shouldhave a melting point between about 50 C. and 110 C., and a penetrometerhardness (ASTM D5-52) below about 15 as measured with 100 grams for 5seconds at ice 25 C, the acid and saponification values beinginappreciable.

The present invention may be better understood by reference to theaccompanying drawins'g in which SIG. 1 is an isometric view of thepresent transfer; an

FIG. 2 is a section on line 2-2 of FIG. 1-.

Referring to the drawings, a backing 10 is coated with the aforesaid wax11 and a design 12 is printed on the exposed surface of the wax. Whileany convenient backing may be used, paper is preferred for economy.Unlike prior wax transfer disclosures, no sizing is required for thepaper before application of the wax and special papers are not required.

The unoxidized waxes of the present invention may be applied to thecarrier backing by any convenient method but preferably by thewell-known hot-melt process. When using emulsions they should beprepared with alkalies or organic amines since they are formed moreeasily and give emulsions of low foam-forming characteristics makingthem easy to apply with conventional paper coating equipment.

The coated paper is printed with a design by conventional printingequipment such as letterpress, rotogravure, and fiexographic presses andwith conventional inks including those made from powdered metals. Theterm design as used herein includes both printing and art work or acombination of both.

The present invention may be more clearly understood by reference to thefollowing examples in which all parts are by weight:

Example N0. 1

FT-200 or FT-BOO, unoxidized Fischer-Tropsch waxes supplied by DuraCommodities, having melting points between C. and C. and a penetration(ASTM D5-52) from a negligible value up to 2 as measured with 100 gramsfor 5 seconds at 25, the acid and saponification values being nil.

The paper is then printed on the wax side with a nitro-cellulose-basedrotogravure ink. After the ink has dried, the design is transferred toMST-53 cellophane by rolling the cellophane, in contact with the design,over a hot plate at 225 F. with mild pressure. The paper backing isimmediately removed while hot, leaving the design firmly attached to thecellophane.

After coating with the wax, the paper will have a glossy appearance,will show no signs of tackiness, and will exhibit excellent inkreceptivity with sharp outline and good ink-drying properties.Substantially all of the ink design will transfer to the cellophane withonly faint staining from the wax without significant distortion.

Example No. 2

Like Example No. 1 except in that the unoxidized Fischer-Tropsch wax isParaflint RG or Paraflint supplied by Moore & Munger, the melting pointsof which range between 90 C. and 100 C. and the hardness ranging from anegligible value up to 5, the acid and saponification values being nil.

The products of the above examples will also transfer with good resultsto material other than cellophane, such as for example, metal foil,wood, fabric, plastic, glass and the like.

The aforesaid waxes are unique in that they afford satisfactory resultsfor most purposes when unoxidized. While ink does not adhere to them sowell, for some purposes this is of only secondary importance.Furthermore the ink adhesion properties may be improved by blending inother materials such as oxidized polyethylene and oxidized -FT wax.

2,989,413 3 4 It should be understood that the above disclosure is about50 C. and 110 C. and a penetrometer hardness for the purpose ofillustration only and that the invenbelow about 15. tion includes allequivalents and modifications falling within the scope of the appendedclaims. References Cited in the file of this patent c aim: 5

1. A heat transfer comprising a backing and thereon UNITED STATESPATENTS a release coating comprising unoxidized Fischer-Tropsch1,739,581 Ellis Dec. 17, 1929 wax and thereon a printed design.1,882,593 Hentschel Oct. 11, 1932 2. A heat transfer according to claim1 further char- 2,219,071 Humphner Oct. 22, 1940 acterized in that saidcoating has a melting point between 10 2,594,547 Fischer Apr. 29, 1952

1. A HEAT TRANSFER COMPRISING A BACKING AND THEREON A RELEASE COATINGCOMPRISING UNOXIDIZED FISCHER-TROPSCH WAX AND THEREON A PRINTED DESGN.